System and method for sensing distance and/or movement

• US 9,019,150 B2
• Filed: 02/20/2012
• Issued: 04/28/2015
• Est. Priority Date: 02/21/2011
• Status: Expired due to Fees

• Current Assignee: Transrobotics, Inc.
• Original Assignee: Transrobotics, Inc.
• Inventors: Alalusi, Sayf
• Primary Examiner(s): Barker, Matthew M
• Application Number:
  US13/400,261
• Publication Number:
  US 20120212366A1
• Time in Patent Office: 1,163 Days
• Field of Search: 342/118, 342/189
• US Class Current: 342/118
• CPC Class Codes: G01F 23/284 Electromagnetic waves
• CPC Class Codes: G01F 23/292 Light , e.g. infrared or ultraviolet
• CPC Class Codes: G01S 13/08 Systems for measuring distance only indirect measurement G01S13/46
• CPC Class Codes: G01S 13/103 particularities of the measurement of the distance G01S13/12, G01S13/14, G01S13/16, G01S13/18 and G01S13/20 take precedence
• CPC Class Codes: G01S 13/325 using transmission of coded signals, e.g. P.S.K. signals
• CPC Class Codes: G01S 13/36 with phase comparison between the received signal and the contemporaneously transmitted signal
• CPC Class Codes: G01S 13/867 Combination of radar systems with cameras
• CPC Class Codes: G01S 13/878 Combination of several spaced transmitters or receivers of known location for determining the position of a transponder or a reflector G01S13/874 takes precedence
• CPC Class Codes: G01S 13/88 Radar or analogous systems specially adapted for specific applications electromagnetic prospecting or detecting of objects, e.g. near-field detection, G01V3/00
• CPC Class Codes: G01S 13/89 for mapping or imaging
• CPC Class Codes: G01S 17/32 using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated
• CPC Class Codes: G01S 17/36 with phase comparison between the received signal and the contemporaneously transmitted signal
• CPC Class Codes: G01S 17/87 Combinations of systems using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 2013/9323 Alternative operation using light waves
• CPC Class Codes: G01S 7/03 Details of HF subsystems specially adapted therefor, e.g. common to transmitter and receiver
• CPC Class Codes: G01S 7/038 Feedthrough nulling circuits
• CPC Class Codes: G01S 7/352 Receivers
• CPC Class Codes: G01S 7/358 using I/Q processing
• CPC Class Codes: G01S 7/41 using analysis of echo signal for target characterisation; Target signature; Target cross-section
• CPC Class Codes: G01S 7/497 : Means for monitoring or calibrating
• CPC Class Codes: H01Q 21/00 : Antenna arrays or systems arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system H01Q3/00

Abstract

A method (e.g., a method for measuring a separation distance to a target object) includes transmitting an electromagnetic first transmitted signal from a transmitting antenna toward a target object that is a separated from the transmitting antenna by a separation distance. The first transmitted signal includes a first transmit pattern representative of a first sequence of digital bits. The method also includes receiving a first echo of the first transmitted signal that is reflected off the target object, converting the first echo into a first digitized echo signal, and comparing a first receive pattern representative of a second sequence of digital bits to the first digitized echo signal to determine a time of flight of the first transmitted signal and the echo.

Claims

1. A method comprising:

transmitting an electromagnetic first transmitted signal from a transmitting antenna toward a target object that is a separated from the transmitting antenna by a separation distance, the first transmitted signal including a first transmit pattern representative of a first sequence of digital bits;

receiving a first echo of the first transmitted signal that is reflected off the target object;

converting the first echo into a first digitized echo signal;

comparing a first receive pattern representative of a second sequence of digital bits to the first digitized echo signal to determine a time of flight of the first transmitted signal and the echo;

transmitting an electromagnetic second transmitted signal toward the target object, the second transmitted signal including a second transmit pattern representative of a third sequence of digital bits;

receiving a second echo of the second transmitted signal that is reflected off the target object;

converting the second echo into a baseband echo signal;

comparing a second receive pattern representative of a fourth sequence of digital bits that is delayed by the time of flight from the third sequence of digital bits in the second transmit pattern to the baseband echo signal to determine temporal misalignment between one or more waveforms of the baseband echo signal and one or more waveforms of the second receive pattern, the temporal misalignment representative of a time lag between the second receive pattern and the baseband echo signal; and

adding the time lag to the time of flight to determine a distance to the target object.

2. The method of claim 1, further comprising calculating the separation distance to the target object based on the time of flight.

3. The method of claim 1, further comprising generating an oscillating signal and mixing at least a first portion of the oscillating signal with the first transmit pattern to form the first transmitted signal.

4. The method of claim 3, wherein converting the first echo into the first digitized echo signal includes mixing at least a second portion of the oscillating signal with an echo signal that is based on the first echo received off the target object.

5. The method of claim 1, wherein comparing the first receive pattern includes matching the sequence of digital bits of the first receive pattern to subsets of the first digitized echo signal to calculate correlation values for the subsets, the correlation values representative of degrees of match between the sequence of digital bits in the first receive pattern and the subsets of the first digitized echo signal.

6. The method of claim 5, wherein at least one of the subsets of the digitized echo signal is identified as a subset of interest based on the correlation values, and the time of flight is determined based on a time delay between transmission of the transmitted signals and occurrence of the subset of interest.

7. The method of claim 5, wherein comparing the first receive pattern includes matching the sequence of digital bits of the first receive pattern to subsets of an in-phase (I) component of the first digitized echo signal to calculate first correlation values for the subsets and matching the sequence of digital bits of the first receive pattern to subsets of a quadrature (Q) component of the first digitized echo signal to calculate second correlation values for the subsets, the first and second correlation values representative of degrees of match between the sequence of digital bits in the first receive pattern and the subsets of the I and Q components of the first digitized echo signal.

8. The method of claim 7, wherein at least one of the subsets of the I component of the first digitized echo signal is identified as a first subset of interest based on the correlation values and at least one of the subsets of the Q component of the first digitized echo signal is identified as a second subset of interest based on the correlation values, and the time of flight is determined based on a first time delay between transmission of the transmitted signals and occurrence of the first subset of interest and on a second time delay between transmission of the transmitted signals and occurrence of the first subset of interest.

9. The method of claim 1, wherein converting the second echo into the baseband echo signal includes forming an in-phase (I) channel of the baseband echo signal and a quadrature (Q) channel of the baseband echo signal, and comparing the second receive pattern includes comparing an I channel of the second receive pattern to the I channel of the baseband echo signal to determine an I component of the temporal misalignment and comparing a Q channel of the second receive pattern to the Q channel of the baseband echo signal to determine a Q component of the temporal misalignment.

10. The method of claim 9, wherein the time lag that is added to the time of flight includes the I component of the temporal misalignment and the Q component of the temporal misalignment.

11. The method of claim 10, further comprising resolving phases of the first echo and the second echo by examining the I component of the temporal misalignment and the Q component of the temporal misalignment, wherein the time of flight is calculated based on the phases that are resolved.

12. The method of claim 1, wherein at least two of the first transmit pattern, the first receive pattern, the second transmit pattern, or the second receive pattern differ from each other.

13. The method of claim 1, wherein at least two of the first transmit pattern, the first receive pattern, the second transmit pattern, or the second receive pattern include a common sequence of digital bits.

14. A system comprising:

a transmitter configured to generate an electromagnetic first transmitted signal that is communicated from a transmitting antenna toward a target object that is a separated from the transmitting antenna by a separation distance, the first transmitted signal including a first transmit pattern representative of a sequence of digital bits;

a receiver configured to generate a first digitized echo signal that is based on an echo of the first transmitted signal that is reflected off the target object; and

a correlator device configured to compare a first receive pattern representative of a second sequence of digital bits to the first digitized echo signal to determine a time of flight of the first transmitted signal and the echo,

wherein the transmitter is configured to transmit an electromagnetic second transmitted signal toward the target object, the second transmitted signal including a second transmit pattern representative of a third sequence of digital bits, and wherein the receiver is configured to create a baseband echo signal based on a second echo of the second transmitted signal that is reflected off the target object; and

a baseband processor that is configured to compare a second receive pattern representative of a fourth sequence of digital bits that is delayed by the time of flight from the third sequence of digital bits to the baseband echo signal to determine temporal misalignment between one or more waveforms of the baseband echo signal and one or more waveforms of the second receive pattern, the temporal misalignment representative of a time lag between the second receive pattern and the baseband echo signal, wherein the baseband processor is configured to add the time lag to the time of flight to determine a distance to the target object.

15. The system of claim 14, wherein the baseband processor is configured to calculate the separation distance to the target object based on the time of flight.

16. The system of claim 14, further comprising an oscillating device configured to generate an oscillating signal, wherein the transmitter is configured to mix at least a first portion of the oscillating signal with the first transmit pattern to form the first transmitted signal.

17. The system of claim 16, wherein the receiver is configured to receive at least a second portion of the oscillating signal and to mix the at least the second portion of the oscillating signal with an echo signal that is representative of the echo to create the first digitized echo signal.

18. The system of claim 14, wherein the correlator device is configured to compare the sequence of digital bits of the first receive pattern to subsets of the first digitized echo signal to calculate correlation values for the subsets, the correlation values representative of degrees of match between the first receive pattern and the digital bits of the digitized echo signal.

19. The system of claim 18, wherein at least one of the subsets of the digitized echo signal is identified by the correlator device as a subset of interest based on the correlation values, and the time of flight is determined based on a time delay between transmission of the first transmitted signal and occurrence of the subset of interest in the first digitized echo signal.

20. The system of claim 18, wherein the receiver is configured to form an in-phase (I) channel of the baseband echo signal and a quadrature (Q) channel of the baseband echo signal, and further comprising a baseband processing system configured to compare an I channel of the second receive pattern to the I channel of the baseband echo signal to determine an I component of the temporal misalignment, the baseband processing system also configured to compare a Q channel of the second receive pattern to the Q channel of the baseband echo signal to determine a Q component of the temporal misalignment.

21. The system of claim 20, wherein the time lag that is added to the time of flight includes the I component of the temporal misalignment and the Q component of the temporal misalignment.

22. The system of claim 21, wherein the baseband processing system is configured to resolve phases of the first echo and the second echo based on the I component of the temporal misalignment and the Q component of the temporal misalignment, and the time of flight is calculated based on the phases that are resolved.

23. The system of claim 14, wherein the correlator device is configured to compare the sequence of digital bits of the first receive pattern to subsets of an in-phase (I) channel of the first digitized echo signal to calculate first correlation values for the subsets and to compare the sequence of digital bits to subsets of a quadrature (Q) channel of the first digitized echo signal to calculate second correlation values for the subsets, the first and second correlation values representative of degrees of match between the first receive pattern and the digital bits of the digitized echo signal.

24. The system of claim 23, wherein at least one of the subsets in the I channel of the digitized echo signal and at least one of the subsets in the Q channel of the digitized echo signal is identified by the correlator device as a subset of interest based on the correlation values, and the time of flight is determined based on a time delay between transmission of the first transmitted signal and occurrence of the subsets of interest in the I and Q channels of the first digitized echo signal.